Sinus Iridum, or The Bay of Rainbows, on the Moon

January 2, 2015

By Andrew Jacob

A composite image of the Moon from the LRO spacecraft. The arrow points to Sinus Iridum. Image by LROC/NASA.

Peter posted a question on our Lights in The Sky page asking: Can I see the Moon’s Bay of Rainbows from Melbourne (S/E Australia)?

Yes, you can see it from Melbourne, and from anywhere on Earth. It is an ancient crater flooded with lava. A section of the crater wall remains covered by lava making it appear like a ‘bay’ opening into Mare Imbrium, the “Sea of Rains”. It is best viewed with binoculars or a telescope around the time of full Moon.